You are 100% correct about the origins. And it was an A+ troll job. The problem now though, is that symbolism evolves and changes. It isn't static. People who are actual white supremacists can now do that troll OK gesture and have plausible deniability afterwards. The troll job was so effective because of that. First, they can make fun of anyone who takes it seriously, and afterwards, they can call anyone who doesn't buy their excuse unhinged. And even if the dumb made up gesture gets co-opted by actual racists jack offs, anyone using it has plausible deniability forever basically .
To me, regardless of how it originated, if someone uses symbolism like that now, after it's all out in the open, they are a racist dick. The meaning and symbolism has changed since the creation. Context is a bitch.